Mechanisms of iron transport has been extensively studied in aerobic microorganisms, but study of iron assimilation in anaerobes has never been investigated. We will examine the strict anaerobe, Desulfovibrio gigas, which has a severe iron problem because it produces H2S during growth. We will seek the presence of ferrous chelating ionophores, analogous to ferric siderophores in aerobes. The black iron storage protein we have is covered in this organism will be examined to determine the manner in which its high iron content is bound. In addition, we will look at the facultative anaerobe, E. coli. We will study the kinetics of iron uptake when it is grown anaerobically and search for the presence of ferrous ionophores. The alteration of iron uptake when the organism is switched from anaerobic to aerobic growth conditions will be investigated. Finally, we will commence investigation of the mechanism by which trace amounts of iron repress siderophore biosynthesis, and in particular, the mechanism by which the amounts of cellular ornithine, the siderophore precursor, is controlled by iron levels. This work should be particularly relevant in view of the fact that anaerobic iron transport must be widespread in nature, i.e., in animal intestinal tract.